Calling function and using data while calling ASM from C

[mist]

Hi,

I would like to call ASM (MASM) from C (GCC). Easy!
Now i would like my asm function to be able to use data and to call functions like printf().
I got two problems: the data section and the call to printf()
I have read examples on internet which are exactly like mine but don't seem to fail. Any help is welcomed.

This problem has been discussed on this forum anyway i can't find a way to compile my executable properly as GCC is also involved.
Thanks to fellow coders.

test.c:

#include <stdio.h>
int64_t asmfunc();
int main() {
asmfunc());
return 0;
}

test.asm:

global  asmfunc
section .data
msg: db "a very inspired message!",10,0
section .text
extern printf
asmfunc:
mov edi,msg
xor eax,eax
call printf
ret

compilation:

nasm -felf64 maxofthree.asm
gcc callmaxofthree.c maxofthree.o

result:

/usr/bin/ld: maxofthree.o: relocation R_X86_64_32 against `.data' can not 
be used when making a shared object; recompile with -fPIC

if i just leave the printf call, removing the .data section and the "mov edi,msg", i get

/usr/bin/ld: maxofthree.o: relocation R_X86_64_PC32 against symbol
`printf@@GLIBC_2.2.5' can not be used when making a shared object;
recompile with -fPIC

Hope my question will not be considered out of subject, my plan is to code mostly in asm with support of C, not the otherway

By the way, if someone knows how to use global variable from the C source inside the assembly function, the answered is welcomed too. I'm quite a noob at C, sorry.

Dear

[mist]

solution has been found! (quite quickly i admit)(but with some external help)

       lea rdi, [rel msg]
          xor rax,rax
      call printf wrt ..plt

between you and me, i also missed a EDI/RDI

[Frank Kotler]

Hi mist,
Welcome to the Forum.
Thanks for sharing the solution with us!
Before I saw that you'd posted the solution I beat on it a bit myself... or it beat on me...
First, typo in your c file: "asmfunc())" has an extra ")". Easily fixed.
Next, a puzzle. My gcc didn't like "int64_t". I think that should be fine. I changed it to just "int" to shut gcc up, but I think it should be fine. Dunno what my problem was there.
I spotted the "edi" instead of "rdi" but didn't change it.
Worked for me!

I was going to suggest "rel". You can put "default rel" in your file to change 'em all. I don't know why it worked for me without it. I don't know why your gcc apparently thought you were trying to make a shared object. I have a lot to learn about 64-bit code!

Anyway, glad you got it working!

Best,
Frank